Method of packing wells



March 10, 1936. w T. WELLS METHOD vOF PACKING WELLS Original Filed Nov.l

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Patented Mar. 10, 1936 UNITED STATES METHOD F PACKING WELLS Walter T.Wells, Glendale, Calif., assignor to The Technicraft EngineeringCorporation, Los Angeles, Calif., a corporation of California Originalapplication November 12, 1932, Serial No.

Divided and this application July '1, l1934, Serial No. 734,1707L 9Claims. (Cl. 16S- 21) The present invention relates to a method ofpacking wells and is a division of my co-pendlng application entitled:Means for packing oil wells and the like; illed: November 12, 1932,Serial No. 642,369. l

The objects of my present invention are:

First, to provide a method of this character which has a wide range ofapplication, it being useful inperforming for such operations asformation testing or testing for shoe leaks, location of water intrusionin oil or gas wells, fractures in cement jobs, and segregation ororientation of oil or water producing zones in bores of great depth,breaking up cement that has been set to facilitate its removal, cleaningthe well bore of mud accumulations, and many other uses;

Second, to provide a method of this character which is readily adaptableto and usable in conjunction with present-day oil well practice andrequires a minimum of special equipment for its execution; and 4 Third,to provide a method of this character which may be easily and quicklyexecuted.

With these and other objects in view as may appear hereinafter,attention is directed to the accompanying drawing in which Figure 1 is avertical cross sectional view of an apparatus designed to execute mymethod, showing the apparatus in position within a well bore; Figure 2is an enlarged sectional view thereof taken through 2-2 of Figure 1illustrating particularlyV the check valve incorporated 'in the samplermeans; and Figure 3 is a diagrammatical view illustrating a modificationof my method wherein hydraulic pressure is utilized.

Referring to the drawing, the numeral I indicates a tubing stringlowered into a well bore 2, here shown as open formation, filled withdrilling iiuid 3, and terminating below an oil producing stratum 4.

The device hereinafter describedis operated in association with adivided tubing string wherein two sections of said tubing are providedwith means permitting relative movement of the sections and saidmovement is utilized to expel a refrigerating agent for the purpose ofsolidifying all water bearing matter cognate to said tubing string.

But one string of tubing is employed and it serves several purposes. thewell dry", that is to say, closed at the bottom to keep it empty ofiluid as it is lowered into drilling iiuid or the like.

It thus provides a conduit for the discharge refrigerating agent atsubstantially atmospheric Said string is run intol pressure. Whensubsequently opened, it affords a means of communication with theproducing zone below the frozen area for the recovery of a sample offluid therefrom, and for circulating, from the mouth of the well, astream of liquid to expedite thawing or to create hydraulic pressure inthe zone below the frozen core. 'Ihe lower end of tubing I, (uppersection) is threaded to receive collars 6 and 'I. Between said collarsis a piston 8, provided with rings 9 and cup leathers II.

Slidable within the tubing is the upper end member I2 of the lowersection of tubing string I.

. Welded or suitably secured to member I2 is a cylinder head I3 to whichis threaded, at I4, one end of a cylinder I6, the opposite end of whichis threaded at Il to a cylinder head I8, provided with a packing glandI3 through which slides the tubing I.

The structure so far described provides a cylindrical chamber 2| whichis loaded, before the device is lowered into the well 2, with arefrigerant 22, which may be anhydrous ammonia, carbon dioxide, sulphurdioxide or other suitably equivalent.

The member I2 is threaded into a bore 23 in a connector 24. Said bore isenlarged from below and tapped to admit therein a threaded collar 26, avalve cage 21, and one end of a pipe 28 provided with perforations 23.

A rigid connection is thus formed between perforated pipe 28 and memberI2 and it results from this that, when pipe 28 encounters the bottom ofwell 2, cylinder I6 is held stationary and the weight of the entireupper section of the tubing string I is eiective to move piston 8through said cylinder and expel the refrigerant 22 through an expansionvalve 3| which, under urge of -a spring 32, normally closes one end of apipe coil 33, here shown as a double coil surrounding the member I2 andterminating in a valve cage 34.

As the weight of tubing string -I moves piston 8 downwardly the spacebehind said piston is illled with drilling uid 36, from well bore 2,which enters through passages 31 and 38 normally closed by a springactuated check valve 39.

Therefrigerant 22, under pressure, unseats expansion valve 3|, passesthrough coil 33, lifts a flapper valve 4I (in valve cage 34) to itsdotted line position and exhausts into member I2 of the dry tubingstring.

The rapid expansion of the refrigerant, thus released, congeals theliquid surrounding the coil 33 and solidiiles an area of considerablesize in the adJacent formation as indicated by the broken line shadedarea A in Figure 1.

'I'his method of sealing or packing an open hole or formation bore,which has no casing, assures a fluid tight seal betwen the tubing stringand a surrounding wall which is completely effective, irrespective ofinequalities or irregularities of surface, or formation characteristics,which so often defeat mechanically operated packers.

'I'he tubing string I has been kept dry up to this point by a. membraneor disc 42 compressed between collar 26 and pipe 23 in a mannerobstructing passage of liquid into member I2.

When the refrigerating action has taken place, a go-devil indicated indotted lines at 43 is dropped through tubing string I, from the mouth ofthe well, and it strikes the top of a piston valve 44, which rests onsaid disc 42 and is thereby prevented from seating in its cage 21 untilsaid disc is broken out as described.

As soon as said disc is broken, fluid in the zone below the frozen areais released at substantially atmospheric pressure, and it rushes intomember i2 of the tubing string, lifting piston 44 until it abuts collar26. Said piston is provided with quadrilaterally disposed channels 46,Figures 2 and 3, which communicate with a bore 41 in collar 26. f

Fluid continues to rise in the' tubing string until it reaches itsnormal head, being relieved of hydrostatic pressure of drilling fluid inthe well by the frozen area 33.

When the pack thaws 33 suillciently to permit raising of the tubingstring, piston valve 44 acts as a foot valve, entrapping the fluidcontent of the tubing, as the lower tapered end of said valve seats incage 21 and closes channels 46.

Check valve 31 prevents escape of drilling fluid from cylinder I6 andsaid fluid, being entrapped, forms a connecting link between the upperand lower sections of tubing string I, automatically responsive to thefirst lifting strain.

Said check valve 31 also provides a means for applying pump pressure topiston 3 as shown in Figure 3. Should it be desirable to augment thepressure provided by the weight of tubing string I, a pump 43 isconnected, by a pipe line 49, to the well 2 which is closed at the mouthas indicated at 5|. As the pump increases the pressure in the Well valve3| is unseated and piston 3 moved downwardly to discharge refrigerant22.

It is of course recognized that heat resulting from compressing of therefrigerant before opening of valve 3| must be dissipated to obtain anefficient refrigerating action in coil 33. This may be accomplished inseveral ways. First, the refrigerant may be introduced in the cylinder2| under pressure; but such pressure being lower than that necessary toopen valve 3|. Then upon applying additional pressure either throughtubing string I or hydraulically through valve 31 the valve 3| is causedto open. The additional pressure need not be such as to heat therefrigerant materially; furthermore, the chamber 2| is quite elongatedand the pressure therein may be maintained fairly uniform after thevalve 3| is open so that a large percentage of such additional heat willbe dissipated through the walls of the cylinder. Very little of thisheat will be absorbed by the chilling coil as heat tends to bedissipated upwardly.

Second, as the refrigerator is lowered, the liquid in the well boretends to maintain an equality `53 under urge of a spring 54.

of pressure between the exterior of the refrigerator and the upper endof the piston 3, providing valve 31 does not offer too much resistance.This pressure increase lifts the refrigerator structure relative to thetubing string moving the piston relatively downwardly and compressingthe refrigerant. In this case as in the first, valve 3| is designed towithstand this pressure. The movement of the piston is gradual and theheat of compression is dissipated to the well fiuid as fast as it isgenerated so that the temperature of the refrigerant does not increasematerially. When the refrigerator is in position, additional prureeither hydraulically or by gravity is applied to open valve 3|.

Third. valve 31 may be designed to remain closed against the pressure ofthe well nuid. After the refrigerator is in position the tubing stringis moved downwardly shifting the piston a predetermined distancecalculated to compress the refrigerant but not open valve 3|, and isthen held until the resulting heat is dissipated; whereupon theadditional pressure is applied.

Pump pressure can also be applied to tubing string I to ush theformation below the frozen zone, or to increase pressure at that point.

A check valve 52 is provided in the piston valve v44 and said valvenormally closes a port However when said check valve is unseated fluidenters the port 53 and finds its way through passages I3 which open intoa bore l1 in valve cage 21, when the piston valve is seated in saidcage.

'I'he piston valve 44, check 82, and cage 21 are also shown anddescribed in my co-pending application for patents, filed September 6,1932, Serial Number 631,781.

In order to prevent accumulation of frost around expansion valve 3| andits orifice I load coil 33 with an inert iiuid containing-no moisture.Said fluid is also placed in the lower portion of pipe I2 to a levelindicated by the dotted line 5B, Figure 1. Said fluid is driven out ofcoil 32 by the release of refrigerant 22 ahead of piston 3.

It will be seen that pipe 23 can be removed from the foot member 24 andother anchoring means substituted therefor.

I employ a standard thread which makes possible the interchangeable useof either a rathole packer of the type illustrated in my copendingapplication Serial Number 634,599, filed September 23, 1932, or ahook-wall packer such as is described in my application Serial Number614,731, filed June 1st, 1932.

The operation of my invention is as follows:

Formation test-During the drilling of an oil well, the bit progressesinto the ground or formation, passing through various strata. The objectis to temiinate the well when a formation has been reached containing asupply of oil or gas in quantity suilicient for practical production.While the well is being drilled it contains a quantity of mud ladenfiuid, known as drilling fluid.

This fluid exerts pressure, dependent upon the height of the fiuid,which opposes the natural pressure of the oil or gas contained in theformation through which the well is being drilled.

Oil is usually encountered in formations at considerable depth and atpressures insumcient to overcome the pressure of the fluid in the well.

As the driller does not know the depth at which oil may be present, andto prevent drilling on past an oil bearing stratum of formation withoutknowledge of its existence, a formation test is made to determine theproductivity at a given depth. y

My apparatus is assembled as shown in Figure 1 and lowered into the well2 on the lower end of tubing string I, the lower section of which ismovable with respect to the upper section.

said movement being limited to .the degree of travel of piston 8 incylinder I6.

When the lower end member 2l of the bottom section encounters the bottomof the well, the weight of the upper section moves piston 3 anddisplaces the refrigerant 22, the rapid dissipation of which lowers thetemperature in the zone surrounding the coil 33 until a pack or seal Ais solidified and seals off the drilling fluid 3 from formation below.

When the well has been packed in this manner, go-devil 43 is droppedthrough tubing string I and -its impact shatters the frangible disc 42,opening the tubing string I to the inux of fluid from the formation 4.Said fluid, being now opposed by-no pressure other than atmospheric,rises within the tubing string I to its natural head or level.

The frozen pack A is allowed to thaw and the tubing string I is raised.Foot valve 44 seats under pressure of the entrapped fluid sample in thetubing and said sample is lifted within s the string.

Water shut op* test.-Before a well is placed on a production basis, astring of casing is set and said casing is cemented around its shoe, orbottom end, and measures must be taken to ascertain the eiilcacy of saidcement seal in excluding extrusion of water from upper levels into oilYproducing formation. Laws, enacted in the interest of the eld as awhole, require .a test furnishing proof that this water shut oil! iscomplete.

A cementitious material is introduced through the casing and allowed toset aroImd the casing and below its lower end for a considerabledistance. The cement plug so formed is then drilled through, the boreextending beyond the casing and into formation below. As it isimpracticable to bail out the casing at great depths owing to danger ofcollapse of casing under external pressure it is necessary to packwithin the casing and near the shoe and thereafter recover a sample ofthe content of formation below.

In this instance, the relatively small volume of iiuid between thecasing and the drill stem need be solidified to effect a pack.

A quantity of refrigerant 22 is injected through a loading bore 59,Figure l, through the cylinder head I3, and said bore is closed by aplug 6I.

The device is lowered as before and the drilling fluid solidified at apoint above the shoe of the casing, go-devil 43 is dropped to open thetubing string I to admit a sample of fluid through pipe 28.v The seal isallowed to thaw and the entrapped sample recovered as previouslydescribed. Y

Removing coated accumulations from formation MIL- Formation walls becomeplastered or encrusted with drilling fluid which impedes filtration ofoil into the bore. The weight of the column of dense fluid and theaction of the boring tool combine to produce this effect.

As the accumulation contains water it can be removed by submitting it'to -alternate freezing and thawing and the solid content of theencrustation will gravitate to the bottom of the well-leaving` the.formation wall in a better condition to exude oil.

. Disintegrationbf cement bodies-It some-l times happens, in a cementingoperation, that cement introduced in plastic state sets prematurely, orimproperly, leaving an obstruction to re-cementing efforts. and noteffectively preventing inilltration of water from above.

Buch bodies can be fractures by expansive treatment a batch ofrefrigerant isolated from the surface, restrained in an inert conditionbut capable upon being released to absorb a predetermined quantity ofheat; and then releasing said refrigerant charge to cause it toundergo-a single refrigerating cycle.

2. The method of extracting heat from a predetermined section of ajwellbore characterized by: introducing opposite the section to undergotreatment a batch of refrigerant isolated from the surface; theninfluencing the. 'r frigerant body to cause it to undergo a refrigeratcycle.

3. The method of extracting heat from a predetermined section of a wellbore characterized by: introducing opposite the section to undergotreatment a batch of compressed refrigerant isolated from the surface;then reducing the eifective pressure against the refrigerant body.

4. The method of forming a congelation plug in a well bore characterizedby: introducing op posite a predeterminedv point in the well bore abatch of refrigerating material isolated from the surface and calculatedto absorb suilicient heat from the surrounding formation while beingdissipated to `divide temporarily by congelation said well bore intoupper and lower zones.

5. The method of obtaining fluid samples from liquid illled well borescharacterized by: causing a refrlgerating charge to undergo a singlerefrigerating cycle while being dissipated and temporarily divide thewell bore by .congelation into an upper and a lower zone; and thencollecting a sample from the lower zone while the well bore is sodivided.

46. The method`of obtaining fluid samples from liquid filled well borescharacterized by: introducing above the region from which the sample isdesired an isolated refrigerant charge restrained in an inert conditionbut capable of being released to absorb a suili'cient quantity of heatto divide by congelation the well bore into an upper and a lower zone;then collecting a sample from the lower zone.

7. The method of obtaining fluid samples from liquid filled well borescharacterized by: introducing above the region from which Ythe sample isdesired, a compressed refrigerant body isolated from the mouth of thewell bore; then reducing the effective pressure against the refrigerantbody whereby the refrigerant body is caused to absorb heat, therefrlgerating capacity of said refrigerant body being calculated toprovide upon completing its refrigerating action a congelation plugdividing the well bore into an upper and a lower zone; then 'collectinga sample from the lower zone.

8. In the art of obtaining fluid samples from well bores wherein thewell bores are divided into upper and lower zones and the fluid samplesare collected from the lower zones, the method of producing suchdivision of a well bore charactera fluid sample from the lower zonewithout du. ized by: introducing at the point ot division a placementoi' nuid from the upper none, char. refrigerant charge calculated toabsorb suillcient terized by: causing a relrigerant to form by `heatfrom the surrounding formation while the congelation a plug dividing thewell bore extecharge is being dissipated to divide temporarily riorly ofthe sampling device and above its inlet;

said well bore into an upper and a lower zone. and discharging thedissipated refrigerant into 9. A method of dividing into an upper andthe sampling device.

lower zone a well bore in which a sampling device WALTER 'n WELLS.

hasbeen positioned for the Purpose of obtaining

